STUDIES
ON THEEFFECT
OF CLAY ANDORGANIC MATTER CONTENTS ON
THEDETERMINATION OF CATION
EXCHANGE PROPERTIES
IN CLAYSOILS
BY THEAMMONIUM ACETATE AND METHYLENE-BLUE
METHODS
Raimo Erviö and Osmo Mäkitie Agricultural Research Centre, Department
of
Soil Science,Tikkurila, Finland
Received November 30, 1968 In a previous study it was observed that the so-called methylene-blue adsorption method of Peter and Markert(1955 and 1961) gave values of cation exchange capacity in Finnish soils comparable tothose obtained by the ammoniumacetatemethod (Mäkitie and Erviö 1966). The correlation coefficient 0.942*** wasat 99.9 % significance level (27 samples ofmineral soils).1
The studies have been continued in thepresent work, where results of both methods arecompared inasoil sample material of claysoils, particularly withrespect tothe effect of the mineral and humuscontentin soilonthe values of the total cation exchange capacity andon the mutual ratios between the exchangeable metallic cations.
Experimental
The soil sampleswerecollected from the Hyvinkää—Nastola arealyingon the highest coastal line of the Litorina Sea in South Finland (Hyyppä 1937). The claymaterial,which is of Glacial origin, contains mostly minerals of mica and weathered materials of illitic type of clay (Salminen 1935, Soveri 1950),as well as of chlorites (Soveri and Hyyppä 1966). These observations have been confirmed in arecent study of topsoil clays of the region ofCentral-Uusimaa, located somewhat south of thearea nowinvestigated (Mäkitie and Virri 1965).
Detailed data of sample material grouped on the basis of decreasing clay content are presented in Table 1. The clay content of the topsoil (0—20 cm) samples of cultivated soils varies from 21 to86 per cent. The names of the soiltypes according to the Finnish
1 Abbreviations used: CEG =cation exchange capacity, MB =methylene-blue, AA=ammonium acetate.
Table 1. Analytical data.
Sample Soiltype Relative
No. o •-
1
o '-R cationsS¥ 3*
O ESS. lä*
Ca*+ Mg»+ K+a b cdefghij
1A Heavyclay 86 13 9.1 5.34 4.18 34.4 28.0 1.9
2 » » » 77 12 7.0 5.26 4.10 30.4 19.2 2.3
3 » » » 74 15 5.4 5.35 4.15 37.7 26.4 2.0
4» » » 73 16 12.9 5.34 4.21 34.5 20.3 1.3
5» » » 72 13 10.7 5.83 4.58 43.8 27.8 2.3
6» » » 68 18 4.8 5.69 4.55 43.4 30.5 2.2
7» » » 67 27 6.9 5.88 4.76 52.2 19.7 2.6
8» » » 64 19 8.4 5.35 4.21 34.0 16.8 2.2
9» » » 62 26 5.5 5.68 4.44 38.2 30.3 2.3
10» » » 62 20 5.3 5.87 4.72 45.8 25.1 1.8
11 B Silty clay 59 36 10.6 5.48 4.25 34.8 13.7 1.5
12» » » 57 35 4.8 5.68 4.51 45.9 16.7 2.9
13» » » 53 35 5.7 5.57 4.37 41.4 16.8 2.5
14» » » 53 31 5.2 5.27 3.98 32.? 15.7 2.2
15» » » 52 20 6.9 5.62 4.51 48.7 10.6 3.2
16» » » 51 45 10.5 5.62 4.55 43.5 15.0 1.1
17» » » 49 43 6.5 5.89 4.69 48.1 19.5 1.8
18» » » 47 35 6.1 5.42 4.24 37.0 13.3 2.7
19» » » 47 36 5.4 5.54 4.25 35.8 25.4 1.9
20» » » 46 39 9.7 5.80 4.73 53.1 11.0 0.4
21 » » » 46 38 6.9 5.55 4.40 36.4 18.2 1.9
22» » » 46 41 5.2 5.47 4.17 39.6 15.7 1.4
23» Sandy clay 46 16 10.7 5.68 4.63 46.9 16.8 1.4
24» Clayeysilt 43 51 12.3 5.48 4.42 42.9 7 8 1.9
25 » Silty clay 43 32 8.4 5.47 4.38 43.8 17.2 1.9
26» Sandy clay 43 20 6.0 5.81 4.69 47.8 17.1 1.9
27» Clayeysilt 40 50 8.2 5.51 4.38 38.4 14.4 2.6
28» Sandy clay 40 31 6.2 5.64 4.43 39.6 12.1 2.3
29 C » » 39 25 11.0 6.22 5.34 63.8 7.6 2.4
30 » » » 38 23 7.9 5.52 4.45 38.8 23.6 1.2
31 » Clayeysilt 35 50 11.6 5.88 4.90 60.1 8.5 1.1
32» Sandy clay 34 37 3.3 5.53 4.31 35.4 17.8 3.2
33 » » » 33 31 8.7 5.83 4.73 51.0 7.1 3.4
34» » » 32 41 10.3 5.39 4.37 40.1 10.1 1.5
35» » » 32 54 7.9 5.07 3.97 19.2 11.8 2.5
36» Clayeysilt 32 56 5.7 5.73 4.66 41.5 11.5 4.2
37» Sandy clay 32 45 3.6 5.31 3.94 33.7 13.9 1.9
38» » » 31 34 5.6 5.57 4.26 35.8 10.2 2.4
39» Clayeysilt 30 56 7.9 5.55 4.53 42.4 13.3 2.0
40» Sandy clay 30 41 7.0 5.24 4.12 30.3 7.5 1.1
41 » » » 30 45 4.7 5.91 4.92 54.1 9.5 2.5
42 » Silt 27 58 3.9 6.81 5.52 66.7 23.8 1.0
43» Silty loam 26 47 9.8 5.32 4.18 30.8 7.7 1.2
44» Sandy loam 22 40 4.1 5.65 4.40 39.7 14.8 1.3
45» Sandysilt 21 54 9.4 6.03 5.12 61.6 7.8 1.3
GroupA;
meanvalues 71 18 7.6 5.56 4.39 39.4 24.4 2.1
GroupB;
meanvalues 48 35 7.5 5.58 4.42 42.0 15.4 2.0
GroupC;
meanvalues 31 43 7.2 5.68 4.57 43.8 12.1 1.2
Methylene-bluemethod
S s? a c + CEC
distribution of 60 »66 c
S'S
“ "m lä-® =-50inCEC% 8 -e o -a c Sg S S8 Extr. g§ Extr.
-g
S 5 Ö* jT-2 O pH o pH
M 4. u 1 X 4 (H W S U d d Mo tCcj
Na H US w £ n w U u £ u *r «n £ cm £
k lmnopqrs tu
0.9 34.8 37.8 24.7 65 33.3 1.23 12.5 6.4 24.3 6.4
0.6 47.5 32.0 16.8 52 27.6 1.58 12.3 6.3 18.6 6.6
1.3 32.6 29.9 20.2 68 23.9 1.43 11.9 6.4 22.5 6.4
1.1 42.8 32.2 18.4 57 27.8 1.70 12.4 6.5 23.0 6.5
0.6 25.5 34.0 25.3 74 28.6 1.58 12.3 6.5 22.0 6.6
0.4 23.5 29.8 22.8 77 20.0 1.42 12.1 6.5 20.2 6.5
0.9 24.6 38.0 28.6 75 25.9 2.65 12.2 6.5 19.9 6.5
0.6 46.4 31.0 16.6 54 23.6 2.02 12.1 6.5 21.1 6.6
0.8 28.4 28.4 20.3 71 22.9 1.26 11.8 6.5 19.6 6.6
0.8 26.5 28.7 21.1 74 22.5 1.82 11.8 6.4 21.4 6.6
0.7 49.3 31.7 16.1 51 21.8 2.54 11.9 6.6 21.3 6.6
0.6 33.9 25.1 16.6 66 16.0 2.75 12.0 6.6 17.6 6.5
0.7 38.6 23.7 14.6 62 14.9 2.46 11.4 6.5 19.6 6.4
0.7 49.1 22.9 11.6 51 17.4 2.06 11.5 6.4 18.5 6.5
0.4 37.1 27.2 17.1 63 18.6 4.59 11.8 6.4 19.8 6.5
0.8 39.6 32.3 19.5 60 19.9 2.90 11.9 6.2 21.6 6.5
0.5 30.1 29.1 20.3 70 14.0 2.47 11.9 6.5 21.4 6.4
0.6 46.4 24.8 13.3 54 17.4 2.78 11.8 6.4 20.8 6.6
0.4 36.5 23.6 15.0 64 13.4 1.41 11.1 6.4 18.5 6.4
0.4 35.1 26.8 17.4 65 19.2 4.83 11.1 6.5 20.4 6.5
0.4 43.1 25.1 14.3 57 15.6 2.00 11.8 6.4 20.0 6.5
0.6 42.7 25.4 14.6 57 12.6 2.52 11.3 6.4 17.5 6.6
0.5 34.4 32.6 21.4 66 16.5 2.79 12.0 6.4 23.3 6.5
0 4 47.0 32.3 17.1 53 17.2 5.50 12.2 6.3 21.9 6.5
0.5 36.6 26.0 16.5 63 14.6 2.55 11.9 6.4 20.3 6.5
0.7 32.5 25.9 17.5 68 16.3 2.80 11.6 6.5 19.2 6.4
0.9 43.7 21.6 12.2 56 13.1 2.67 11.8 6.4 18.5 6.5
0.5 45.5 21.9 11.9 54 14.5 3.27 11.3 6.5 14.7 6.4
0.7 25.5 29.4 21.9 74 14.4 8.39 12.1 6.5 21.4 6.5
0.6 35.8 24.7 15.8 64 15.5 1.64 12.0 6.4 22.0 6.6
0.7 29.6 31.5 22.2 70 14.0 7.07 12.1 6.4 21.9 6.5
0.5 43.1 16.6 9.4 57 10.4 1.99 9.6 6.5 14.3 6.6
0.5 38.0 22.3 13.8 62 11.1 7.18 11.6 6.5 19.4 6.6
0.6 47.7 22.4 11.7 52 11.5 3.97 11.8 6.3 20.8 6.5
0.7 65.8 22.8 7.8 34 10.8 1.63 10.8 6.3 18.0 6.4
0.9 41.9 19.1 11.1 58 8.2 3.61 10.3 6.4 15.0 6.4
1.2 49.3 15.2 7.7 51 10.6 2.42 9.5 6.5 13.6 6.5
0.7 50.9 20.8 10.2 49 11.2 3.51 10.6 6.5 16.0 6.4
0.7 41.6 21.9 12.8 58 11.2 3.19 10.9 6.4 17.7 6.4
0.4 60.7 22.5 8.8 39 10.2 4.04 10.9 6.4 18.9 6.6
0.5 33.4 19.9 13.2 66 11.9 7.21 10.7 6.6 15.4 6.4
1.3 7.2 20.7 19.2 93 9.9 2.80 11.3 6.6 17.7 6.6
0.9 59.4 18.9 7.7 41 8.7 4.00 11.2 6.3 17.6 6.7
1.0 43.2 15.0 8.5 57 7.5 2.68 9.1 6.4 12.0 6.5
0.5 28.8 24.9 17.7 71 8.3 7.90 12.0 6.5 20.4 6.4
0.833.3 32.221.5 66.725.6 1.6111.94 6.4521.24 6.52
0.640.1 26.615.9 60.016.2 2.7311.66 6.4219.72 6.47
0.741.4 21.712.9 58.610.9 3.6110.97 6.4417.76 6.49
classificationare given in column b. The organic matter content varies from 3.3 to 12.9 per centand the pH-values from 5.1 to 6.8 in soil: water (1: 2.5) suspension. The samples were pre-treated by air-drying, sieved through a 2-mm round-holed sieve and homo- genized.
Methods. The methylene-blue adsorption method usedwas principally thesame asreported previously (Peter and Markert 1955,Mäkitie and Erviö 1966). Two sub- samples, twoand five grams,were weighed and separately treated with 50 ml of aqueous 0.4 % methylene-blue solution (»Methylenblau
B»/E.
Merck AG).The ammonium acetate method has also been described in detail previously. A molar ammonium acetate solution (pH adjusted to 7) was used as an extractant for repeated extractions of the cations (Schollenbergerand Simon 1945, Mäkitie and Virri 1965).
The total cation exchange capacity was determined by exchanging the ammonium ions with M potassium chloride solution, and the liberated ammonium ions were analyzed by Kjeldahl-d istillation.
Hydrogen peroxide (30 %) was used for oxidizing the organic matter in soil samples where the CEC of pure mineralmatterwastobe determined.
The absorption was measured with aBeckman Model DU spectrophotometer with 10-mm cellsatawavelength of 510 millimicrons (slit width 0.055 mm).
The particle size distribution analysiswascarriedoutby the sieving and pipettemethod, where organic matter was eliminated by the hydrogen peroxide treatment and sodium pyrophosphate wasused as adispersingagent.
The pH determinationswerecarriedoutby means ofaRadiometer PHM 4c potentio- meter with aglass electrode.
The determinations of the exchangeable hydrogen and of the organic matter content werecarriedoutby thesame methodsaspreviously (Mäkitie and Erviö 1966).
CECasdetermined by the methylene-blue method
The CEC was determined in two ways, i.e. two and five grams of soilwere taken for measuring the adsorption of the dye. The concentration of theMB-solution, the dilution and the wavelength for absorptivity measurement werethesame for bothamountsof soil.
Compared with the AA-method, the values obtained with two grams of soil by the MB- method gave somewhat better correlation (r = o.B6***) than those with five grams (MB-method) (r = o.B4***). The best correlation (r = o.BB***) exists between thetwo MB-methods. The differences,however, arenotstatistically significant. The average ratio between the CEC-values (meq/100 g) obtained by the MB-method withtwo grams and five grams of soilwas 1.7to 1.0. The increasing adsorption with the wider extracting ratio is duetoa morecomplete exposure of the surface of soil particles, aphenomenon observed before as a natural result ofmore effective exchange when the concentration of the ex- changingcation is increased. The process of exchange is incomplete in thecase of the five gram samples while with thetwo gram samples the CEC-values approach those obtained by the AA-method. The relative values obtained by these three methodsare0.4—0.7—1.0.
By the MB-method the increase in the fineness of the soil and humus content also increases the dye adsorption. Results of experiments with five soils andten soil-dye ratios are shown in Fig. 1.
In spite of the parallel shape of thecurves, the relative dye-adsorption of different soils varies considerably with the soil-dye ratio. In coarsersoils (e.g.curve 5) the effect of the soil-dye ratio is relatively lowas indicated by themore linear shape of the curve. With increasing clay and humus contents (e.g. curves 3 and 4) the adsorption becomes more dependent on the soil-dye ratio. The effect of humus is relatively more pronounced than that of clay as indicated by acomparison ofcurves2 and 3to curve4. It is apparent that when extracting with 50 ml of 0.4 percent MB-solutionno morethan3—4 grams of soil should be used.
The pH-value 6.80 of the buffered MB-solution decreases during the extraction gener- ally to6.2—6.6 (MB 5 g) and to6.4—6.7 (MB 2 g).
The
effect of
the clayfraction
The CEC of normal soil is mostly duetothe clay fraction, particularlyto the colloidal clay fraction (Whitt and Baver 1937, Hallsworth and Wilkinson 1958). Silt also in- creasesthe CEC tosomeextent(Render 1965), although inoursoils its effect isrelatively insignificant (Heinonen 1960).
The CEC-values arein ahighly significant correlation to the clay content of the soils under study (see below). The best correlation (r =o.79***) obtained by the AA-method is significantly higher (at 95 % signif. level) than the lowest (r = 0.56) obtained by the MB-method.
Fig. 1.Absorbance of dyed soil solution (MB-method) as a function of soil-dye ratio in five soils with varying clay and humus contents.
The CEC-values were determined also by the AA-method after a hydrogen peroxide treatment in order to eliminate the effect of organic material (Table 1,p). A very clear correlation (r=o.9s***) was nowobtained between the CEC of the mineral fraction and the clay content of soil. It seems that the whole obtainable capacity is dueto the clay in the mineral fraction only (the fraction attributabletoregression, 91 per cent).
This result confirms the observation of Heinonen (1960) regarding to the insignificance of silt. According to Pratt (1957) about 15% of the totalcontent of organic material cannotbe eliminated by the hydrogen peroxide treatment. This effectmust be taken into
accountin addition tothe possible effect of the silt fraction. Ifwe suppose the whole CEC of the mineral fraction tobe due tothe clayfraction, the meanCEC of the clay fraction in our population is 30.2 meq/100 g clay, and the range of variation22.7—36.3 meq/100 g.
The
effect of
the organic matterSoil organic matter causes a considerable increase in the CEC as shown by several investigators (Hissink 1926,Mitchell 1932,Williams 1932,Yuanet al. 1967, etc.). The effect of organicmatter ontheCEC,incontrast to that of clay, ismoreevident if the CEC is determined by the MB-method than by the AA-method.
Methodfor CECdetermination
Correlation coefficient
AA I clay content MB (2 g) I » »
MB (5 g) I » »
o.79***
0.56*»*
o.63***
AA I humuscontent
MB (2g) I » »
MB (5 g) I » »
0.54»**
o.66***
o.sB***
The best correlation (r = o.66***) between the CEC and the humus content was obtained when the CEC was determined by the MB-method using2 g samples. The MB- method with5 g samples gave asomewhat lower correlation (r = o.sB***) and the AA- method (r = o.s4***) asignificantly lowerone (t = 2.81**) than the method first men- tioned.
The
effect of different
cationson the CECOnanaverage 41.7 percentof the CEC is duetoexchangeable calcium which pro- portion is somewhat higher than the average in finer soils (groupA,Table 1,h) and slightly lower than in coarser soils (group C). However, the variation in the calcium percentage is relatively small and only inseven cases there isadeviation exceeding 10 units of percen- tage from the mean.
Magnesium in the exchange complex varies to a much greater extent than calcium (Table 1, i). The values ofexchangeable magnesium vary from 7,1 to 30.5 per
cent, the average being 17.3. The amount of exchangeable magnesium clearly decreases with a decreasing clay content so that in group A it is 24.4 % and in group C only12.1 %.
The ratio between the calcium and magnesium ions de-
pends clearlyon the clay fraction (Fig. 2 and Table 1,q). The values 1.6,2.7 and 3.6were obtained for the ratio Ca;Mg in groupsA,B and C,respectively. The correlation between this ratio and the claypercentage is statistically significant (r= o.s6***).
In thepopulationin Fig. 2 eight samples ofan exceptionally high Ca:Mg ratiocanbe distinguished. These apparentlyrepresent soils with heavy liming and without magnesium fertilizing and with arelatively lowcontent of natural magnesium.
The Ca:Mg ratios obtained are in agreement with those of earlier investigations of Finnish soils. For example, the ratio calculated from the data of Aarnio (1942) was 1.68 for heavy clays (18 samples) and 2.91 for sandy clays (24 samples). The corresponding ratios calculated from Heinonen’s (1956) datawere 2.20 for heavy clays (5 samples) and 3.28 for silty and sandy clays (8 samples). The increasing role of Mg in the exchange complex withadecreasing particle size is apparently due tothe relatively high Mg-content of clay minerals in Finnish clays. This is also supported by the results ofKaila and Ryti (1968).
Potassium and sodium play a minor part in the exchange complex of Finnish soils (Table 1,j and k) making only 2.4 (1.7 -f- 0.7) per cent of the CEC on an average. The variation range for K is 0.4—4.2 and for Na 0.4—1.3 percent.The percen- tageof exchangeable K decreases withadecreasing claycontentand is lowest in groupC, whilenoclear effect ofclay onsodiumcan be noticed. Regarding to exchangeable Mg, K and Na, the values of Marttila (1965) obtained by thesame methodareinagreement with thepresentresults while her values for Caaresomewhat higher.
Exchangeable hydrogen covers on an average 40
%of
the cation exchange capacity. In groupA, where the claycontent is high, the hydrogen percentage is the lowestFig. 2. Correlation between Ca2+/Mg2+ ratio and clay content of soils.
Fig. 3. Correlationbetween the pH of soil suspension and base saturationpercentage.
(mean value33 %). It isexceptionally low in sample No 42 due tothe high Ca and Mg contents.The average base saturationpercentage is67, varying from 34 to93. A positive correlation between the saturationpercentageand the pH of soil suspension was obtained, r =o.B2*** (pHH 0) and r = o.77*** (pHv/KCI) asshown in Fig. 3.
Summary
The correlation between CEC-values obtained by ammonium acetateand methylene- blue adsorption methods is relatively good (r = o.B6***). The latter method gives, however, about 30 percent lower values for exchangeable cations.
The extraction ratio used in the dye adsorption method hasaclear effecton the level of the CEC-values. More complete adsorptionwas obtained with wider ratios. With in- creasing clay and humus contents the adsorption becomes more dependent on the soil- dye ratio. The effect of humus ismore pronounced than that ofclay.
The CEC-values obtained by the ammoniumacetatemethodwerein better correlation
to the clay content of soils than the values obtainedbythe dye-adsorptionmethod, while the latter valueswerebetter correlatedtothe organicmatter contentof the soil.
The percentages of exchangeable potassium, sodium and, especially, of magnesium, decrease when the claycontentdecreases, while that of calcium increases slightly.
The ratio between exchangeable calcium and magnesium depends on the claycontent of the soil (r = o.s6***) so that the value of the ratio Ca:Mg increases when the clay
contentdecreases (Table 1,q).
REFERENCES
Aarnio, B. 1942.Überdie Tone Finnlands und ihre Eigenschaften11.Die austauschbaren Basen. Agrogeol.
Pubi. 53: 1—24.
Hallsworth, E.G.& Wilkinson, G.K. 1958.The contribution ofclayandorganic matter tothe cation exchange capacity ofthe soil.J.Agr. Sci. 51:I—3.
Heinonen,R. 1956. Magnesiumin tarpeesta Suomenpelloissa. Summary: Magnesiumrequirements in Finnish agriculture. Agrogeol.Pubi. 65: 1—32.
—»— 1960.Über die Umtauschkapazität des Bodens und verschiedener Bodenbestandteile inFinnland.
Z. Pfl.ernähr. Diing. Bodenkunde 88: 49—59.
Hissink, D.J. 1926.The relation between the valuespH, Vand S(humus) ofsomehumus soils. S (humus) andVof these soils with pH = 7.Theequivalent weightof the humussubstance. Transac. of 2nd Comm.Int. Soc. Soil Sci. Groningen. Vol.A: 198—206.
Hyyppä,E. 1937. Post-glacialchanges of shore-line in South-Finland. Bull. Comm. Geol. Finlande N:o 120: 1—225.
Kaila, A.& Ryti, R. 1968.Calcium, magnesium andpotassium in clay, silt and fine sand fractionsof someFinnish soils.J.Sci. Agr. Soc.Finland40: I—l3.1—13.
Marttila,U. 1965. Exchangeable cationsinFinnish soils. Ibid. 37: 148—161.
Mitchell,J. 1932.Theorigin, natureandimportanceof soil organic constituents having base-exchange properties. J. Amer. Soc. Agr. 24: 256—275.
Mäkitie,O. &Erviö, R. 1966. Comparative studies on the cation exchangeproperties of mineral soils bythe methylene-blue adsorptionmethod and by the ammonium acetate method. Ann. Agric.
Fenn. 5: 260—266.
—»— & Virri, K. 1965. Onthe exchange characteristics ofsome clay soils in the Middle Uusimaa.
Ibid. 4: 277—289.
Peter, H. & Markert, S. 1955.Eine Schnellmethode zurBestimmung der Sorptionseigenschaften von Ackerböden. Z.landwirtsch. Versuchs- u. Untersuchungswes. 1: 582—596.
■» » 1961. Die Bestimmung der MB-Sorption mit gepufferter Methylenblaulösung zurAus- schaltungdespH-Einflusses auf die Höhe derSorptionwerte. Ibid. 7;426 —441.
Pratt, P. F. 1957. Effect of fertilizers and organic materialsonthecation-exchange capacity ofanirri- gated soil. Soil Sci. 83: 85 —89.
Renoer, M. 1965.Berechnungder Austauschkapazität der organischen undanorganischen Anteile der Boden.Z.Pfl.ernähr. Diing. Bodenkunde 110: 10—26.
Salminen, A. 1935.Onthe weathering of rocks and thecompositionofclays. Selostus; Kallioidenrapau- tumisesta ja savien kokoomuksesta.Agrogeol. Julk.40: 1—174.
Schollenberoer, C.J.&Simon, R. H. 1945.Determination of exchangeable basesinsoil ammonium acetate method. Soil Sci. 59: 13—24.
Soveri, U. 1950.Differential thermal analyses ofsome quaternaryclaysof Fennoscandia. 103p.Helsinki.
» & Hyyppä,J. M. I. 1966.Onthemineralogyof fine fractions ofsomeFinnish glacial tills. State
Inst. Techn. Res.Finland, Pubi. 113.
Whitt, D. M. & Baver, L. D. 1937.Particle size inrelation to base exchangecapacity andhydration propertiesof Putnam clay.J.Amer. Soc. Agr.29: 905—916.
Williams,R. 1932.Thecontribution ofclay and organic matter to the base exchange capacityof soils.
J.Agr. Sci. 22: 845—851.
Yuan, T. L.,Cammon, N.& Leiohty,R. G. 1967.Relative contribution of organic and clay fractions to cation-exchange capacityof sandy soils from several soil groups. Soil Sci. 104; 123—128.
SELOSTUS:
SAVIAINEKSEN JA HUMUKSEN VAIKUTUKSESTA SAVIMAAN
KATIONINVAIHTOKAPASITEETIN MÄÄRITTÄMISESSÄ NS. AMMONIUMASETAATTI-
JA METYLEENISINIMENETELMILLÄ Raimo Erviöja Osmo Mäkitie
Maatalouden tutkimuskeskus, Maantutkimuslaitos, Tikkurila
Tutkimuksessa käsitellyt maat ovat glasiaalisavia pohjoiselta Uudeltamaalta. Kaikki näytteet ovat muokkauskerroksesta. Maistaonanalysoitu kationinvaihtokapasiteettins. ammoniumasetaatti- jametylee- nisinimenetelmillä sekä eri kationien vaihtuvat määrät. Metyleenisinimenetelmä perustuu väri-kationin adsorpoitumiseenmaahiukkastenpintaan.
Ammoniumasetaatti- ja metyleenisinimenetelmän antamat kationinvaihtokapasiteettiarvot ovat varsinhyvässäkorrelaatiossa keskenään (r=o.B6***), joskin saadut milliekvivalenttimäärät 100gmaata kohti ovat eri tasoa arvojen keskinäisensuhteenollessa noin 1:0.7.
Metyleenisinimenetelmässä huiskutuksessa käytetty sopiva maamäärä, ts.huiskutusväljyys, vaikuttaa kuitenkin ratkaisevasti saatuun vaihtuvien kationien meq-määrään ollen sitä merkityksellisempi, mitä enemmänsavi- ja humusfraktiota maanäyte sisältää.
Ammoniumasetaattimenetelmällä saadut CEC-arvot korreloivat hiukan paremmin näytteen savi- pitoisuudenkanssa kuin MB-menetelmällä saadut,kun taas MB-menetelmän CEC-arvot ovatjonkinver- ran paremmassavuorosuhteessa näytteenhumuspitoisuudenkanssa.
Vaihtuvienkationien, Mg, K ja Na, %-osuudetkaikista vaihtuvista kationeista vähenevät näytteiden savipitoisuuden laskiessa,kun taas Ca-kationin osuuställöin kasvaa lievästi. Mg-kationillamainittusuun- tausonvoimakkain.
Vaihtuneitten Ca-ja Mg-kationien suhdeonriippuvainen (r=o.s6***) näytteen savipitoisuudesta siten,ettäsuhdeluku Ca/Mgonsitäsuurempi, mitä vähemmänsavea maasisältää (taul. 1,q).
